Status: Error, ResponseCode 421, Host not reachable.

Status: Error, ResponseCode 421, Host not reachable.

Hello, we have problems with our zoho mail accounts when sending emails after 40 minutes of being sent, these are returned under the following error message:


This message was created automatically by mail delivery system. 

THIS IS A WARNING MESSAGE ONLY. 

YOU DO NOT NEED TO RESEND YOUR MESSAGE. 

The original message was received at Wed, 30 May 2018 09:06:21 -0700 

----- The following addresses had fatal errors ----- 
[Status: Error, Address: <compras@bijoulapuertahotel.com>, ResponseCode 421, Host not reachable.] 

Message will be retried for 4 more day(s) 

----- Transcript of session follows ----- 

Received:from HPSISTEMAS01 (201.209.43.27 [201.209.43.27]) by mx.zohomail.com 
    with SMTPS id 15276936565927.520469067032991; Wed, 30 May 2018 08:20:56 -0700 (PDT) 
Message-ID:<!&!AAAAAAAAAAAYAAAAAAAAAPfCvdF6MehJqEf2NpCU4wnCgAAAEAAAAA/N8QjLmp5Fud2K7jxqeHsBAAAAAA==@bijoulapuertahotel.com>
Date:Wed, 30 May 2018 11:20:55 -0400 
From:"Sistemas Bijou" <sistemas@bijoulapuertahotel.com> 
To:"'Ernesto Arenas'" <compras@bijoulapuertahotel.com> 
Subject:prueba de correo 
Content-Type:multipart/related; 
    boundary="----=_NextPart_000_0000_01D3F808.485A9880"


Please ask for help to solve this situation

Thank you